The DX and DXG serial port connection is the same as the K2.
I wrote up the K2 with pictures fairly recently.
Set the forum prefix index to "K2", click the 'show threads' button -
Currently it is the most recent thread.
Note that the K2, DX, and DXG use a non-standard, low voltage, serial port.
But the connection point supplies a reference for the I/O interface.
Translation:
You will want a low voltage to usb adapter that accepts an external reference.
But there isn't much point of my repeating the contents of that thread here.

Just use the prefix filter to find it.